Background: Women diagnosed with breast cancer experience high levels of psychological disorders ranging from depression, anxiety, maladjustment to the disease, and decreased self-confidence to different emotional disturbances and fears of recurrence and mortality. The present study aimed to investigate the mediating role of cancer self-efficacy in the relationship between health literacy and social support with health-promoting behaviors in women with breast cancer.
 Methods: In this descriptive-correlational study, the convenience sampling method was employed to select 282 women diagnosed with breast cancer in Ahvaz, Khuzestan Province (Iran) in 2021. The participants were asked to answer the Health-Promoting Lifestyle Profile II (HPLP-II), Iranian Health Literacy Questionnaire, Social Support Survey, and Cancer Behavior Inventory. Path analysis was adopted to analyze data in AMOS software.
 Results: The results revealed there was a significant relationship between perceived social support with health-promoting behaviors (P=0.004) and cancer self-efficacy (P=0.001) in women with breast cancer. There was a significant relationship between health literacy and cancer self-efficacy in women. According to the results, the mediating role of cancer self-efficacy in the relationship between perceived social support and health literacy with health-promoting behaviors was found to be significant in women with breast cancer (P=0.001).
 Conclusion: Accordingly, the research model had a desirable fit. The findings of this research showed the effective role of cancer self-efficacy in the outcome of social support and health literacy to increase health-promoting behaviors in women with breast cancer.